1. Field of the Invention
The present invention is in the field of containers and more particularly relates to a lid for a container, the lid having a shape that facilitates stacking of the containers, having a structure that permits it to be cleaned for reuse, and having an integral pump for use in evacuating air from the container. The design of the lid facilitates its use by handicapped persons.
2. The Prior Art
The nearest known prior art is U.S. Pat. No. 2,890,810 issued Jun. 16, 1959 to Rohling. This patent discloses a vacuum pump that is an integral part of a lid that is removable from a container. The vacuum pump includes a chamber closed on one side by a deformable membrane. A force applied manually against the deformable membrane reduces the volume of the chamber, thereby forcing air out of it through a flap-type valve. When the manually-applied force is released, the chamber expands to its original size, with the assistance of a compressed spring in one embodiment or by the elasticity of the membrane in another embodiment, while air is drawn into the chamber from the container through a second flap-type valve. The patent describes the cementing together of its parts. Although a protective disc is provided to shield the air intake from the contents of the container, it is clear that some of the contents could lodge under the disc or could splash into the air intake and be drawn into the pump, where they might decay or impart an undesirable taste to food that is later stored in the container.
To the present inventor it seems axiomatic that if the lid is to be reusable then it must be easily cleaned to avoid contamination of later-stored contents.
In U.S. Pat. No. 3,672,114, issued Jun. 27, 1972, Sacks describes a device for evacuating containers. In his device a bellows is cemented to a lid. A flap-type check valve is provided at each end of the bellows, which is manually operated to evacuate the container. The presence of the bellows makes it unlikely that the containers can be stacked.
In U.S. Pat. No. 4,016,999, issued Apr. 12, 1977, Denzer describes a piston-type pump that is part of the lid. Denzer also provides a vent for relieving the vacuum.
In U.S. Pat. No. 4,249,583 issued Feb. 10, 1981, Lundbladh describes a device for evacuating a container. Although his device bears a superficial similarity to that of Denzer, the crucial difference is that in Lundbladh the piston-type pump is separable from the lid which makes it practical to stack the evacuated containers.
In U.S. Pat. No. 4,278,114 issued Jul. 14, 1981, Ruberg describes a pump that, like Lundbladh's, is separable from the lid of the container to facilitate stacking of the containers. However, Ruberg's pump, unlike that of Lundbladh, is arranged so that the suction stroke occurs as the piston is pushed toward the lid so that the force applied to the piston is transmitted to the seal between the pump and the lid thereby producing a stronger sealing action.
As will be seen below, the pump of the present invention is intended to remain a part of the lid and in this regard the present invention more nearly resembles that of Rohling. However, unlike the lid of Rohling, the lid of the present invention is structured in such a way that it can readily be disassembled for cleaning.